Electric control system



Patented May i3, i912? UNITED STATES PATENT OFFICE ELECTRIC'CONTROL SYS TEM' Frederick D. Van Lew, Bronxville, N. Y. Application June 23, 1945, Serial No. 601,102

12 Claims.

This invention relates to an electric control system which is responsive to a predetermined change in rate of variation oi' a, condition.

The invention is applicable to battery Icharging systems, chemical process control systems, or the like. in which a condition may initially vary, but nally reaches a stable state which may indicate the completion of the process. In charging certain types of storage batteries, for eirairnole2 the voltage rises or varies continuously as the charge progresses and becomes substantially constant when the battery 'm vfully charged. The charge is completed when the voltage remains constant for a certain period.

An object of the present invention is to provide an automatic control which responds to a predetermined change in the rate of variation of a voltage or other condition.

Another object is to provide a system which is actuated automatically when the condition under measurment remains constant for a predetermined period of time.

Another object is to provide an automatic means to interrupt the charging circuit of a storage battery when the voltage characteristic indicates completion of the charge.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In one embodiment, the control circuit is actuated when the battery voltage ceases to rise and remains constant for a predetermined, period of time. The control circuit may be connected to break the charging circuit so as to stop the charge automatically at the proper time. This ls accomplished by means of time selectors and relays connected to scan the position of the voltrneter indicator at predetermined intervals and to actuate a, relay when there is no change in reading between successive scannings. The scanning may be eiected by contacts, magnetic control, photoelectric control. or other means, including a follow-up mechanism, as will be described.

.Although the nove features which are be= lieved to be characteristic of this invention are pointed out more particularly .in the claims appended thereto, the invention itself will be better understooc` oy referring to the following description taken in connection with the accompanying drawings in which a specific embodiment thereof has been set forth for purposes ci illustration.

In the drawings:

Fig. 1 is a schematic diagram of a control system embodying the present invention;

(Cl. S20- 40) 2 Fig. 2 is a detail View of the battery thermo stat; and

Fig. 3 is a detail View pf another embodiment of the contact arm and drum.

Referring to the drawings more in detail, the invention is shown .as applied to a control tem for controlling the charging circuit to a storage battery lll. The morage battery lo is shown as connected to positive and. negative l l and I2 respectively which are connected to any suitable source of charging current such as.l D. C. meins or a motor generator set or e, rectifier oi standard type. In the embodiment shown. the charging circuit is controlled by a circuit breaker M'which is normally open and is provided with a holding coil I5 for holding the circuit breaker in closed position.

The battery I0 is shown as connected by leads 20 to the driving element 2l of a voltrneter having a moving arm 23 and a drum scale ict; of the usual. construction. The voltmeter E2 is assumed to be of the type developing suiicient torque to permit the arm 23 to actuate a Incchanical contact or, if desired, the arm 23., may control a relay circuit magnetically or electro statically, or the voltmeter may be of the photoelectric control type. In any event, the contacts, whether relay controlled or mechanically controlled, are represented in Fig. l as contacts mounted on s. drum 26 and positioned to be che gaged by `a roller 2'! carried on a shaft 28 at tached to the arm 23 and so arranged that the roller sweeps over the surface of the drum as the arm 23 swings over the scale 2li.

The drum 26 is connected by a shaft 3@ to be driven by an electric motor 3! such. as motor or a synchronous motor of the ciccia motor type which is arranged to drive the drum speed, for example, of two revolutions per minute.

One of the contacts 25 is connected by e, line 35 to one side of a main 3S which may be cori-u nected to a source of either alternating or direct current for controlling the motors and relays to be described. The other contact 25 is connected by line 3l to a normally open contact of a lay 40. One supply lead to the motor connected to a second normally open Contact of the relay 40. The other supply lead is of tno motor 3! is connected to a normally yclosed corn tact 45 of a. second relay 4E.

The iirst relay d isy provided with 50 and 5l which are adapted to engage contacts 38 and 43, respectively, when the relay is enerra gized. The armature 5,0 is connected by a line 52 to the energizing coil 53 of the second relay 46, the return lead 54 of which is connected to the return line of the main 36. The relay 40 is provided with an energizing coil 56, one side of which is connected by a line 51 to one of a pair of contacts 58 which are connected to be closed by a timer cam 59. The return lead of the coil 56 is connected by a line 60 to the main 36. The armature 5| of the relay 40 is connected by a line 6| to the main 36.

The second relay 46 is provided with an armature 65 normally engaging the contact 45 and an armature 66, shown as a second armature, which is connected to close a normally open contact 61. The contact 61 is connected to the line 62 and the `armature 66 is connected by a line 66 to the lirn`31 so that the contact 61 constitutes a holding contact for the relay 46. It is to be understood that the various contacts of each relay may be actuated by a common armature provided with separate circuit controls if desired.

The armature 65 oi' the relay 46 engages a front contact 10 which is connected by a line 1| to the energizing coil 12 of a third relay 13. The other side of the coil 12 is connected by a line 14 to one of a pair of contacts 15 which are connected to be closed by a timer cam 16. The third relay 13 is provided with an amature 11 which is connected by a line 18 to the battery supply line i2 and with a .normally closed contact 19 which is connected by a line 60 to contacts |0| controlled by a thermostat 6| and thence to the holding coil 5 of the circuit breaker |4 and thence by line 82 to the battery supply line on the battery side of the circuit breaker |4. The thermostat 8| may be short-circuited by a switch 63 when its use is not required.

The timer cams 59 and 16 are driven continuously by the shaft 95 of a motor 90 which may be of the direct or of the synchronous type and may operate to drive the timer cams at a speed of, for example, two revolutions per hour. The motor 90 is supplied by lines 9| and 92 which are connected to the main 36. The other of the pairs of contacts 58 and 15 are connected by a line 96 to the line 92.

The timer cams 59 and 16 are shown as driven by the shaft 95 of the motor 90 and close the contacts 58 and 15 for predetermined periods of time during each revolution of the shaft 95. If the motor 90 is designed t0 cause the timer cams 59 and 16 to make one complete revolution in thirty minutes, the timer cam 16 may be designed to close the contacts 15 at the end of 28 minutes and hold these contacts closed for a period of about 30 seconds. The timer cam 59 may close the contacts 58 at the end of 30 minutes and may hold these contacts closed for a period of approximately 2 minutes. Any standard type of repeating-timing switch may be used for this purpose. A rotary cam-operated timer has been shown merely as representative.

Referring to Fig. 2, thethermostat 8| is shown as comprising a bimetallic element |00 controlling contacts |0| and mounted in a casing |02 of insulated material such as rubber, which is provided with a iiange |03. The casing |02 is designed to pass within the ller opening |04 of the cover |05 of the storage battery until the device rests upon the iiange |03. The thermostat is thus immersed in the electrolyte and responds to the electrolyte temperature.

In the operation of this device, closing of the contacts 58 by the BO-minute-timer cam 59 energizes the coil 56 of the first relay 40 and holds the coil energized for the stated period, for exam- 4 ple 2 minutes. Actuation of the relay 40 closes the contact 36 and thereby completes a connection from the line 31 through the armature 60 and line 52 to the coil 53 of the second relay 46. The coil 53, however, is not energized until the contacts 25 are closed by the roller 21. The closing of the contact 43' by the armature 5| also completes the circuit from the main 36 through the line 6|, armature 5|, contact 43, lead 42 to the motor 3|, thence through the motor to the lead 44, back contact 46 of the relay 46, armature 65 and lead 54, back to the main 36, thereby causing the motor 3| to operate and to drive the drum 26.

As soon as the drum 26 reaches a position such that the contacts 25 are closed by the roller 21, the circuit is completed to the coil 63 of the second relay 46, as above described, causing this relay to operate. Operation of this relay breaks the back contact 45 and interrupts the circuit to the motor 3|, thereby stopping the drum 26 in position to leave the contacts 26 and 21 clod. Actuation of the armature 65 closes the iront contact 10 and sets up a circuit through the coil 12 of the third relay 13 to the contacts 15. The circuit, however, is not completed unless the contacts 16 are closed by the timer cam 16. Actuation of the second relay 46 also closes the contact 61 and sets up a holding circuit through the lines 66 and 31 and the contacts 25 which holds the relay 46 energized until the contacts 26 are broken.

The armature 66 of relay46 must close the contact 61 before the contact 36 of relay 46 is opened. This may be accomplished by making the amature 50 of the slow release type.

The holding coil I6 of the circuit breaker |4 is normally energized through thermostat 6| and the contact 16 and armature 11 of the third relay 13, thereby maintaining the battery on charge. However, when either the relay 13 or the thermostat 6| is actuated, the circuitl to the holding coil I5 is broken and the circuit breaker |4 is allowed to open, thereby disconnecting the battery I0 from the charging circuit. The thermostat 6| is designed to operate only when the temperature of the electrolyte within the battery exceeds a predetermined value which indicates conditions harmful to the battery.

After the relay 46 has been set up as above described, it will be held in energized condition as long as the contacts 25 remain closed, even though the contacts 56 are opened at the end of the two minute period. Ii' the contacts 16 are made by the timer cam 16 while the contacts 25 are held closed and the circuit to the third relay coil thus set up, the relay 13 will be actuated to break the contact 19 and open the circuit breaker |4 as above mentioned. Il', however, the contacts 25 are broken before the timer cam 16 closes the contact 15, the relay 13 will not operate. It will thus be noted that the relay 13 is operated only if the contacts 25 remain closed for the period of approximately 28 minutes after the actuation of the contacts 56 by the timer cam 59 and until the contacts 15 are closed by the timer cam 16. If this occurs, it indicates that the roller 21 and arm 23 are in the same position as at the beginning of the 28 minute period which is the assumed condition to indicate the completion of the battery charge. If during this 28 minute period, the voltage of the battery varies suiiiciently to open the contacts 25, the relay 13 will not operate and the cycle is repeated at the next closing of the contacts 56.

It the contacts 25 havzA been broken by movement of the arm 23 and roller 21 prior to the subsequent closing of the contacts 15 by the timer cam 18, there is no actuation of the relay 13, but the relay 46 will release. However,v when the contacts 5l are again closed by the timer cam 53 at the end of the thirty minute period, the relay 4l is actuated to complete the driving circuit to the motor 3| as above described and causes this motor to drive the drum 26 until the contacts 25 are brought under the new position of the roller 21. When this occurs, the motor 3| is stopped y by actuation of the relay 46 and the circuit is set up for test at the end of the next twenty-eight minute period. It there is suilicient movement of the pointer 23 between test periods to open the contacts 25 the control relay 13 is not actuated, but the motor 3| is again actuated when contacts Il are closed to bring the contacts 25 into engagement with the roller 21 in its new position and to set the device up for the subsequent test when the contacts 15 are again closed by the timer cam 15.

The system thus acts to check the position of the arm 23 at predetermined intervals and acts to operate the relay 13 if there has not been sumcient movement o1' the arm 23 between successive check periods to break the contacts 25.

'I'he sweep of the contacts 25 is such that the contacts do not remain closed if a predetermined voltage change takes place. The movement of the arm 23 and of the roller 21 may be made such that, for the range under test, the normal voltage change in the battery at the end of each thirty minute charge will be surlicient to open the contacts 25, and when the contacts 25 remain closed for the thiry minute period the storage battery is in fully charged condition.

The roller mechanically, but mayv comprise a magnetic or capacitive control member which energizes the control circuit for the relay 48 by varying the impedance of the control circuit when in register with the contacts 25. A photoelectric control member may also be used, for example an electronic voltmeter. Mechanical y contacts have been shown for simplicity only.

In the embodiment of Fig. 3,' for example, the contact drum I I is shown as provided with a contact ring and a contact strip ||2 which makes contact with the ring and extends across the face of the drum i i0. The drum is provided wtih a peripheral groove ||4 across which the strip ||2 extends. A brush ||3 makes contact with the ring and is connected to the line 31 which corresponds to the line 31 in Fig. 1.

A meter |20 is provided with a shaft |2| carrying a pointer I5 which is arranged to swing across the face of the meter in the usual manner. The lead 35 (Fig. l) is connected to the shaft |2| and so makes contact with the pointer 5.

In the i'orm shown the end of the pointer ||5 is bent over and carries acontact strip H6 which is adjustably attached thereto by screws ||1 extending through elongated slots ||8 in said strip H5. 'I'he strip IIS carries a point ||9 of contact material such as platinum, which rests in the groove ||4 and makes contact with the strip I2 when in registration therewith.

The U-shaped bend of the pointer H5 provides resilience to hold the contact H9 in the groove I |4. The tension may be adjusted by the screws ||1. 'I'he drum lill corresponds to the drum 28 of Fig. 1 and is connected to be driven in a similar way about an axis coinciding with 21 need not close the contacts z5 A a second circuit rplete a circuit therebetween. The form shown however eliminates one brush contact.

It is to be understood that the system is applicable to various uses, for example to certain chemical processes wherein the control is dependent on the rate of change of a condition. It

is also evident that the c ontrol may be reversed and may respond to a predetermined change during the timed interval and be non-responsive to constant conditions during such interval. The system may oi' course be connected to respond to current changes as well as voltage changes and may be varied in other respects as will be appar.. ent to a person skilled in the art.

Although a specific embodiment of the invention has been shown for purposes of illustration, it is to be understood that the invention is only to be limited in accordance with the scope of the following claims.

What is claimed is: y

1. A system responsive to variations in the rate of change of a movable member, comprising a circuit controlelement actuated by said member, control element movable in a path to cooperate with said rst element when in registration therewith, circuit means actuated periodically to bring said second element into registration with said first element, relay means, and timed means operating a predetermined time interval after said circuit means and connected to actuate said relay if said elements are still in registration.

2. A system responsive to variations in the rate of change oi' a movable member, comprising a circuit control element actuated by said member, a second circuit control element movable in a path to cooperate with said iirst element when in registration therewith, driving means for said movable element, circuit means including a timed switch to actuate said driving means, means responsive toregistraticn of said elements to stop said driving means, relay means, and circuit means including a second timed switch operatK1 ing a predetermined time interval after said rst switch to actuatey said relay means if said ele7 ments are still in registration.

3. A system responsive to variations in the rate of change of a movable member, comprising a circuit control element actuated by said member, a second circuit control element movable in a path to cooperate with said first element when in registration therewith, driving means for said movable element, a pair of switch means, a com troller to actuate said switch means in a predetermined time sequence, driving means for said controller, means responsive to one of said switch means to actuate said first driving means, means responsive to registration of said elements to stop said rst driving means with said elements in registration, and circuit means responsive to reg-j istration of said elements and to actuation of said second switch means.

4. A system responsive to variations in the rate of change oi' a movable member, comprising a circuit control element actuated by said member, a second circuit control element movable in a path to cooperate with said ilrst element when in registration therewith, driving means for said movable element, a pair oi switch means, a controller to actuate said switch means in a predetermined time sequence, driving means for said controller, means responsive to one of said switch means to actuate said first driving means, means responsive to registration of said element to stop said First driving means with said elements in registration, relay means, and circuit means responsive to registration of said elements and to actuation of said second switch means to actuate said relay means.

5. A system responsive to variations in the rate of change of a movable member, comprising a circuit control element actuated by said member, a second circuit control element movable in a path to cooperate with said first element when in registration therewith, driving means for said movable element, a pair of switch means, a controller to actuate said switch means in a predetermined time sequence, driving means for said controller, a control circuit for said first driving means including a normally open contact and a normally closed contact, a relay to close said normally open contact, means responsive to one of said switch means to actuate said relay and thereby energize said first driving means, a, second relay to open said normally closed contact, a second normally open contact on said first relay, circuit means responsive to closing of said last contact and to registration of said elements to actuate said second relay and thereby open said normally closed contact and stop said first driving means, a holding circuit for said second relay responsive to registration of said elements, a normally open contact actuated by said second relay, and a control circuit including said last contact and the second timed switch.

6. A voltage responsive system comprising a voltage responsive device having a movable arm, a contactor actuated by said arm, a drum having contacts to engage said contactor and movable to followup said contactor, drive means for said drum, a pair of timed switches, means ac- 'tuatlng said switches in predetermined time sequence, circuit means including said first timed switch to actuate said drive means, means to stop said drive means when said drum contacts engage said contactor, and a control circuit actuated by said second timed switch, said control circuit including said drum contacts and being energized only when said drum contacts engage said contactor during the operation of said second timed switch.

7. A voltage responsive system comprising a' voltage responsive device having a movable arm, a pair of circuit control elements, one of said elements being carried by said arm, follow-up mechansm carrying the other of said elements, a control circuit responsive to registration of said elements, timed means to actuate said follow-up mechanism periodically to bring said elements into registration, timed switch means actuated periodically a predetermined time interval after said rst timed means, and a control circuit actuated in response to said timed switch means and to registration of said elements.

8. A battery charging circuit control system comprising a battery charging circuit, a control device for interrupting the charge including a relay, a voltage responsive device connected to respond to the battery voltage, a pair of circuit control elements, means actuated by said voltage responsive device to shift one of said elements as a function of voltage, follow-up means for the other of said elements, a control circuit responsive to registration of said elements, timed means to actuate said follow-up mechanism periodically to bring said elements into registration, timed switch means actuated periodically a predetermined time interval after said first timed means, a control circuit actuated in response to said timed switch means and to registration of said elements, and means responsive to said control circuit to actuate said relay and interrupt the charge.

9. A storage battery charging circuit control system, comprising a charging circuit, a control relay therefor, a voltmeter connected to respond to the battery voltage, means periodically set as a function of the reading of said voltmeter, and means responsive to two successive unchanged settings of said last means to actuate said control relay for interrupting the charge.

10. A storage battery charging circuit control system, comprising a charging circuit, a control relay therefor, a voltmeter connected to respond to the battery voltage, means periodically set as a function of the reading of said voltmeter, means responsive to two successive unchanged settings of said last means to actuate said control relay for interrupting the charge, a thermostat connected to respond to battery temperature. and means responsive to said thermostat to actuate said relay fol interrupting the charge.

11. A control system comprising a device having a movable element, a control circuit. means periodically settable as a, function of the position of said element, and means responsive to two successive unchanged settings of said last means to actuate said control circuit. g l

12. A control system comprising a device having a movable indicator arm, a contact member carried by said arm, a second contact member, follow-up means to bring said members into contact, timed means to actuate said follow-up means at predetermined intervals, a circuit including said contact elements, and timed means to energize said circuit at predetermined intervals after each actuation of said first timed means for testing the condition of said contact members.

FREDERICK D. VAN LEW.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

